Spiral stairway



Sept. 2, 1930;

A. L. WOODBRIDGE I SPIRAL STAIRWAY Filed May 12, 1928 Patented Sept. 2,1930 UNITED STATES ARTHUR L. WOODBRIDG-E, OF CHICAGO, ILLINOIS SPIRALSTAIBWAY Application filed May 12, 1928. Serial No. 277,116.

ers, and railing supports secured to the faces of the risers and havingno connection with the other elements of the construction. In thisinvention it has been the purpose to obtain a novel construction whichwould en- 15 able the removal and replacement of any element therein incase of damage without disturbing the remainder of the installation.

Also in case a new location for this stairway should be desired, or forany other reason it is necessary to dismantle and reset the stairway, itmay be done with a minimum amount of time and labor.

Heretofore, it has been usual to provide a tread having sleeves,collars, hubs, etc., secured thereto which of necessity must be slippedover the end of the upright support. It is apparent that in case areplacement is necessary at an intermediate point, it may be necessaryto disassemble the entire stairway. In other instances, split bearingshave been employed and it has been necessary to assemble these hearingsto the risers and later to assemble this construction on the upright,thereby consuming an excessive amount of time and labor.

I The present invention contemplates the use of plurality of risersstamped and formed of a sin le sheet of material and having proyisionswhereby the risers may be directly attached to the central upright. Thisconstruction of course minimizesthe amount of time and labor necessaryin its assembly and lessens the cost of manufacture. Further, all theelements of the construction have been standardized so that it ispossible to manufacture in large quantities for use in any inst.llation; as for example, the treads may be employed ineither aright-hand or lefthand stairway the railing supports are made up instandard lengths and have two holes drilled therein of a predeterminedspacing to be used in any installation regardless of the height of theriser; and the railing may be sized and curved according to theinstallation before being shipped from the factory, all of whichminimizes the amount of time and labor required at the time ofinstallation, and minimizes the cost of production at the factory.

One of the objects of this invention is to provide a spiral stairway inwhich the treads of the stairway are of uniform design for either aright-hand or left-hand stairway.

A further object of this invention is to a provide a spiral stairway inwhich the treads of the stairway are cast of any suitable material suchas iron.

A further object of this invention is to provide a spiral stairwayinwhich the treads are of uniform size for use in any installation, andregardless of the height of the riser.

A further object of this invention is to provide a closed riser spiralstairway.

A further object of this invention is to provide a spiral stairway inwhich the risers are stamped and formed from sheet metal with a minimumof waste.

A further object of this invention is to provide a spiral stairway inwhich the risers so are inclined from a vertical plane which permits ofa wider tread in a limited space thereby affording more toe room, andalso permitting the use of the same tread for both right and left-handspirals.

A further object of this invention is to provide a stairway in which thetread may be of minimum weight and strength due to the tread beingcarried on the top flange of the front riser and on the top of the lowerflange of the riser next above which also increases thestrength andsafety of the stair Way since the treads rest on top of the flanges andare not suspended on bolts, screws, or rivets therefrom.

A further object of this invention is to provide a stairway in whicheach of the risers is secured directly to the main support.

A further object is to provide a stairway that can be conveniently builtupwardly from the bottom in a practically completed condition, wherebyno scaffolding or auxiliary supports are required for the workmen ormaterials in the erection of the stairway, the completed portion thereofprogressively serving the purpose of a support for men and materials asthe worlr of erection proceeds.

A further object of this invention is to provide a spiral stairway whichis efficient, safe, durable and capable of being economi callymanufactured in large quantities or on a production basis for use invarious installations.

Further objects and advantages will be apparent from the description anddrawings forming a part of this specification to which reference may nowbe had for a more complete understanding of the nature and scope of thisinvention, in which drawings:

Figure 1 is a front elevational view of the spiral stairway as embodiedin this invention;

Fig. 2 is an enlarged elevational View of a portion of the same;

Fig. 3 is a perspective view of a portion of the spiral stairway;

Fig. l is an enlarged sectional view taken on the line l-et of Fig. 1;and

Fig. 5 is a top plan view of the entire structure.

Referring now more particularly to the drawings, the circular stairwaycomprises a central upright 10, preferably made of a three inch steelpipe. The risers 11 are preferably stamped from a single sheet of metaland are formed with an upper flange l2 and a lower flange 13, saidflanges being disposed substantially at right angles to the body of theriser and transversely of the axis of the central upright 10. Theserisers are secured directly to the central tubular upright 10, aresupported thereby, and eX- tend radially therefrom and round about thesame in spiral formation. The treads 14: are preferably cast of asuitable material such as iron and rest on the top of the upper flange12 of the front riser and on the top of the lower flange 13 of the rearriser so as to be cxteriorly detachable.

As shown more particularly in Fig. 4, the riser 11 is inclined withrespect to a vertical plane. In order to secure the riser 11 to thetubular upright support 10, a projection or flange 15 is formedpreferably integrally with the riser and is of such a shape as toconform wit-h the contour of the upright. It will be noted particularlyin Fig. 3 that this flange has a peculiar curvature, due to the factthat the support and riser 11 do not occupy the same vertical planes.Flange is held to the support preferably by means of screw bolts 16, andthese bolts not being in a vertical plane with respect to the tubularmember. afford a stronger construction.

A railing support 17, having two holes of a predetermined spacing, issecured to the face of the riser l1 and at the outer end thereof bymeans of screws and bolts projecting through the spaced holes in therailing support 17 and extending through the riser 11. This support isinclined at its lower end to fit the inclined surface of the riser andextends vertically from the upper end of the riser to be secured at theupper end of the support to a pivotal bracket 18, which latter is inturn fixed to the railing 19. The railing 19 is preferably formed of aone and onehalf inch pipe and the railing support 17 is preferablyformed of a three-fourths of an inch square rod, although it is to beunderstood that this device is not to be limited to these specificdimensions, they being mercly for illustrative purposes.

The tread let is provided with notches 20 on each outer corner. Thelower end of the railing support 16 rests on the flange 13 and engagesone of the notches of the lower tread l t and also engages the other ofthe notches 19 in the upper tread 14. The risers 11 are provided withholes of the same predetermined spacing as exists in the support 17 andbolts 21 are inserted therethrough to fasten the supports to the risers.A brace 22, fastened at one end by the lower bolt 21 to the riser,extends to be fastened at its upper end to the tread 14 at a point nearthe outer edge thereof and adjacent to one of the notches 20. A bolt 23extends through the tread and the upper end of the brace 22 to securethe same together, the head being preferably countersunk in the tread inorder to be removable froin the upper side thereof. Screw bolts 2dfasten the edges of the treads to their respective flange heads.

In erecting and installing the stairway, the parts having beenpreviously fabricated in the shop and shipped to the place ofinstallation, the central column is first erected and secured at the topand bottom. The bottom and lower risers are then successively attachedto the column and the treads dropped into position on their supportingflanges of the risers and are bolted in place. Each step is thuscompleted from the bottom up. As the height of the completed stepsincreases, these completed steps are used by the work men as a supportfrom which to continue the erection thus requiring no scaffolding or thelike. The railing supports are then applied, and the railing itself putin position and secured to the railing supports or up rights.

The construction thus extremely sii'nple and important advantagesresult. The risers being attached to the central column after itserection, it is not necessary to slip collars, sleeves, hubs, etc., overthe end of the column before or after erection. The column as erectedis'devoid of all extraneous members and thus is less dillicult totransport, handle, and erect and renders unnecessary the time, care,labor and annoyance of applying such devices to the column.

The risers being individually attached, repairs may be made and brokenor injured treads or other parts replaced without disassembling thewhole stairway. Castiron treads are uniformly used in these stairways asthe treads are of irregular shape and the waste would be too great ifthey were out from sheet metal. Being of castiron the treads may bedamaged by having heavy articles dropped on them, particularly duringthe erection of the building. By this con struction, however, they maybe readily and individually replaced.

The support of the treads continuously along their front and rear edgesby the two flanges of the risers, and the fact that they do not performany individual supporting function in the stairway structure, enablesthem to be made comparatively thin and light, thus reducing the weightof the installation as a whole, making less weight to be handled inmanufacture, shipping and installation, and resulting in an economy ofmaterial, time, labor and expense all around.

The risers being inclined to the rear, ordinarily one inch,gives an inchwider tread than the standard tread and affords more toe room, which isof considerable advantage in spiral stairways where the space isnecessarily limited. Moreover, in such stairways, it is desirable tiatthe treads overhang the risers about an inch at the. front edge. Thestandard req irement is that there be twelve treads to the completecircle.

It is also of advantage to make the tread the same for both right andleft-hand spirals. In this construction by inclining the risers, andsecuring the railing supports to the risers instead of to the treads,and notching the corners of the treads, the tread is capable of use witheither right or left-hand spiral stairways while preserving the frontoverhang and the wider tread. The tread thus becomes a. satisfactorystanoard for all stairways having the same length of step, a matter ofevident impo tance to the manufacturer and economy to the purchaser.

In such stairs, the riser or height of th steps varies with therequirements of the particular installation, and this is taken care ofin this invention by the risers, which, being cut or stamped and formedfrom sheet metal, may be made to vary in height according to theparticular requirements.

The risers are closed preventing one from seeing between the steps andpreventing the feet of the user from being caught therein, thus addingto the safety of the stairway and the feeling of security one has inusing it.

The end flange, which is secured to the central column, is preferablyformed integral with the body of the riser, so that extra parts,brackets, orattachments are unnecessary, and the manufacture anderection are correspondingly simplified and the appearance of thecompleted stairway is enhanced. These risers maybe made as strong asdesired, usually they are formed from No. 12, 14 or 16 gauge steelplate, and serve the multiple purpose of forming the risers of thesteps, the supporting brackets for the structure from the central columnand the front and rear edge supports for the treads.

lifter an upper riser is secured in position, the tread is merely laidor dropped into position on the two flanges by which its weight iscarried, while the securing bolts are put in place and tightened. Thisconstruction further permits of the treads being exteriorly detachable.It isthus not necessary to lift it up into positionv and to hold itthere from beneath the structure and over the heads of the workmen whilethe securing bolts are inserted and tightened. The work of erection istherefore less strenuous and more conveniently carried out. By thisarrangement, also, the load carried by the tread is not supported on afew bolts which may eventually be sheared by use as would be the case ifthe tread were suspended from beneath, and thus much stronger and saferbesides being easier to install and maintain.

The steps of the stairs thus comprise only the two parts or members, therisers and treads; the one, the treads, are standard and alike for allstairs, the other, the risers, are the same types for all stairs. Theproblems of manufacture are thus reduced to minimum, the shipment ofmaterials is facilitated, and the work of erection is correspondinglysimplified and reduced, the workmen having only a few pieces to applyquickly, become skilled and rapid in the work, and a cheaper class oflabor may be utilized.

The railing supports or uprights, being merely bolted to the front ofthe risers and not passing through or being attached to the treads, arequickly and easily applied. The belt holes at their lower ends are ofstandard location for all stairs, regardless of the height of therisers, and being of standare length, they may be fabricated for stockand used as required. They are not bent at the point adjacent the top ofthe riser, until the height of risers for the particular stairway isknown, but otherwise all stairs including both right and left and may bemanufactured and stocked in advance.

When these uprights or supports are applied, the previously bent railingis placed and adjusted in position and the uprights secured thereto.This railing may be bent in the shop also where suitable machinery forthe purpose is at hand, and therefore, larger pipe such as one andone-half inch pipe may standard for 1 ill) be used, Whereas if it isnecessary to do the work of bending at the installation, a much smallerpipe must be used and it is then bent only with great difficulty. Thelarger pipe makes the railing stronger, and the structure as a wholemore rigid and enduring and of better proportions and appearance.

The parts of the complete structure are few in number and simple indesign. When erected and bolted together a strong, rigid stairway isproduced. It is comparatively light in weight, and economical tomanufacture, install and maintain. Furthermore, a closed riser spiraltype of stairway is secured without the addition of extra parts and awider tread than normal is provided.

Cast treads made from a single pattern may be used for all stairs,whether right or left-hand and regardless of the height of the riser. Iprefer, also, to make the upper surface of the treads withdiamond-shaped protubc'anees corresponding in form, location and size tothe diamonds in the so-called diamond plate steel of commerce of whichpractically all such spiral stairway platforms are made.

lVhile but a single embodiment of this invention is herein shown anddescribed, it is to be understood that the invention is not to belimited to that specific structure since various modifications may beapparent to those skilled in the art without departing from the spiritand scope of this invention, and therefore, the same is to be limitedonly by the scope of the appended claims and the prior art.

I claim:

1. A spiral stairway comprising a central upright, risers securedthereto and extending radially therefrom in spiral formation and havingupper and lower lateral flanges, and separate exteriorly detachabletreads supported on the top of one of said upper flanges and on the topof said lower flange of said riser next above.

2. A spiral stairway comprising a central upright, risers securedthereto and extending radially therefrom in spiral formation and havingupper and lower lateral flanges integrally formed thereon, and separateexteriorly detachable treads supported on the top of one of said upperflanges and on the top of said lower flange of said riser next above.

3. A spiral stairway comprising a central upright, risers radiatingtherefrom in spiral formation and having upper and lower lateralflanges, said risers having a projecting portion integrally formedthereon for attachment with said upright, and separate exteriorlydetachable treads supported on the top of one of said upper flanges andon the top of said lower flange of the riser next above.

4:. A spiral stairway comprising a central upright, risers radiatingtherefrom in spiral formation and having upper and lower lateralflanges, said risers having projecting portions individually detachablysecured to said upright, and separate exteriorly detachable treadssupported on thg top of one of said upper flanges and on the top of saidlower flange of the riser next above.

5. A spiral stairway comprising a central upright, risers radiatingtherefrom in spiral formation and comprising a main body portion havingupper and lower lateral flanges thereon, and separate treads supportedon the top of one of said upper flanges and on the top of said lowerflange of said riser next above, said main body portion being inclinedwith respect to the axis of said central upright.

6. A spiral stairway comprising a central upright, substantiallyZ-shaped risers radiating therefrom in spiral formation, and separateindividually detachable treads supported on the top of the upper portionof one of said risers and on the top of the lower portion of the risernext above said risers being individually detachable from said upright.

7. A spiral stairway comprising a central upright, substantiallyZ-shaped risers radiating therefrom in spiral formation, said risersbeing formed of a single sheet of material and having projectingportions integral therewith for engagement with said central upright andlaterally detachable therefrom, and separate individually detachabletreads supported on the top of the upper portion of one of said risersand on the top of the lower portion of the riser next above.

8. A spiral stairway comprising a central upright, risers securedthereto and extending radially therefrom in spiral formation and havingupper and lower flange members, separate treads supported on andextending beyond the top of one of said upper flanges and on the top ofthe lower flange of the riser next above, a railing, and supportssecured to the outer end of the faces of said risers for supporting saidrailing, said treads having cutaway portions at their outer corners forproviding clearance for said supports whereby any element of saidstairway may be detached therefrom without disturbing the remainder ofthe installation.

9. A spirm stairway comprising a central column, step risers securedthereto and individually detacnable and extending radially therefrom inspiral formation, and separate inch v idually detachable treadssupported on and between and carried by said risers.

10. A closed riser spiral stairway comprising a central column, spirallyarranged steps surrounding the said column each of said steps comprisinga closed riser and a s parate exteriorly detachable tread, said risersbeing rigidly secured to said central column and said treads carried byand between the front and rear risers.

11. A spiral stairway consisting of a series of spirally arranged steps,cast treads therefor, and means for supporting said treads alongsubstantially the entire front and rear edges.

12. A spiral stairway comprising tread supports secured to a centralsupporting column and having upper and lower flanges, treads supportedon the top of one of said upper flanges and on the top of said lowerflange next above, railing supports secured 'to said tread supports, anda railing secured to the upper ends of said railing supports.

13. A spiral stairway comprising a central supporting column, treadsupports secured to said column and having a lower lateral flange,treads supported on the top of one of said supports and on the top ofsaid lower flange of said support next above, railing supports securedto said tread supports, and a railing secured to the upper ends of saidrailing supports.

14. A metal spiral stairway comprising a central supporting column, steprisers secured at their inner ends to said column and extending radiallytherefrom in spiral formation, step treads separate from the risers,each tread extending between the upper edge of one riser and the loweredge of the next adjacent riser and being secured to said risers andsupported and carried thereby.

15. A metal spiral stairway comprising a central upright, risers securedthereto and ex tending radially therefrom in spiral formation and havingupper and lower lateral flanges, and separate treads, each tread beingsupported at its forward edge on the top of one of said upper flangesand atits rear edge on the top of the lower flange of the riser nextabove.

16. A metal spiral stairway comprising a central supporting column andsteps secured to said column and extending radially therefrom in spiralformation, each step c0mpris ing a riser and a tread, each of saidtreads extending between and being supported by two adjacent risers.

In witness whereof, I have hereunto subscribed my name.

ARTHUR L. WOODBRIDGE.

